No references can be found for the recovery of hydraulic energy from deep water or other liquids. However, a method for recovering hydraulic energy from the unlimited supply available in deep ocean water is disclosed in my U.S. Pat. No. 5,009,069. Thermal methods have also been proposed for many years for extracting power from surface and deep sea water and most recently have been considered in a series of Ocean Thermal Energy Conversion (OTEC) Conferences which were sponsored by the Ocean System Branch Division of Central Solar Technology, U.S. Department of Energy, and published as proceedings of those Conferences.
None of the many OTEC systems proposed have proved to be practical. They failed because they all require huge warm water flows, as large as 7450 Kg/Sec/MWe, massive structures to process them, vast and expensive heat transfer surfaces and deep water pipes of excessively large diameter. A pipe of about 140 feet in diameter was proposed to recovery 400 MWe of electrically generated potential. The prior art systems are also susceptible to bio-fouling by marine growth which markedly reduces their heat transfer capacity Because of these noted limitations OTEC did not receive the approval of the industrial community; as of this writing there are no facilities in construction or in operation utilizing the prior art OTEC systems.
It has long been known that liquids under pressure can be saturated with dissolved gases. Dissolved gases have been found in deep ocean water. Indeed, the presence of dissolved gases in the water used in OTEC systems was always considered to be undesirable. In such systems one must remove the non-condensable gases to raise the dew point of the water vapor to a temperature above 42.degree. F. to effect condensation of the water vapor. In my U.S. Pat. No. 5,009,069 I teach that when water containing these dissolved gases is extracted from deep ocean water through a vertical conduit the gases form a foam which has a lower bulk density than that found in the body of deep water and is therefore more buoyant. The foam moves upward through the conduit and can be used to produce electrical energy. However, prior to the present invention, the prior art had not recognized that this phenomenon can be utilized to produce energy from liquids found inland.
It is not necessary to find gas containing liquids in deep cavities. One can dissolve gases in liquids by injecting the gases into the liquid under pressure. The stability of gases in liquids depends not only upon the pressure, but also upon the chosen gas and liquid. The literature reports the solubility of nitrogen, oxygen and carbon dioxide in a variety of liquids. The absorption coefficients of these gases in water and six common organic solvents is shown in the following table:
______________________________________ ABSORPTION COEFFICIENTS OF GASES IN ORGANIC SOLVENTS GAS N.sub.2 O.sub.2 CO.sub.2 ______________________________________ SOLVENT Water 0.015 0.028 0.88 Carbon disulfide 0.049 -- 0.83 Chloroform 0.120 0.205 3.45 Ethyl alcohol 0.130 0.143 3.00 Acetone 0.129 0.207 6.50 Ethyl ether 0.240 0.415 5.00 Benzene 0.104 0.163 -- ______________________________________
The reported data suggests that the solubility of nitrogen and oxygen in a broad range of organic liquids, for example alcohols and glycols, exceed by approximately six and maybe up to ten times their solubility in water. Because of this increased solubility alcohols and glycols could be used in place of water or in aqueous mixtures for a liquid containing dissolved gases. However, the art has not recognized that such liquids could be used to produce electrical energy.
A low cost system for recovering energy from deep water found inland, free of the negative effects of the weather which is a concern of OTEC ocean installations, would be very useful and effective. It is also worth noting that the present invention of recovering energy from the deep water would not have any negative effects on the environment. Liners are utilized to prevent any contaminated water or other liquid in my system from seeping into another body of water in close proximity to my deep cavity.